Precursor Preparation to Promote the Adsorption of Mg‐Al Layered Double Hydroxide

Abstract

This study presents an interesting phenomenon of the simultaneous occurrence of adsorption and synthesis of Mg–Al layered double hydroxide (Mg–Al–LDH) by stirring a precursor in an aqueous solution with methyl orange (MO) as target adsorbate with the precursor prepared by first milling Mg(OH)2 for 1 h followed by another 3 h milling with Al(OH)3.The prepared precursor and LDH samples were characterized by a set of analytical methods including X‐ray diffraction (XRD), thermogravimetry/differential scanning calorimetry (TG–DSC), and Fourier‐transform infrared (FT–IR). The maximum adsorption capacity (Qm) of MO by the prepared precursor sample was 1110.2 mg/g, much higher than that from the synthesized LDH sample. Engineering application may be expected from the easy preparation of such precursor as adsorbent to purify the tremendous amounts of dye wastewater.

Precursor preparation of Zn–Al layered double hydroxide by ball milling for enhancing adsorption and photocatalytic decoloration of methyl orange

“…The excellent adsorption performances of the Mg-Al LDH precursor 18 and ettringite precursor 19 were reported in our previous papers. In this work, the precursor of Zn-Al LDH also shows outstanding adsorption efficiency toward MO.…”

“…The mechanism of enhanced adsorption. The enhanced adsorption performance of the Mg-Al-OH LDH precursor toward MO was reported in our previous paper, 18 in which no MO intercalation reaction was observed because the OH À anion of the precursor of Mg-Al-OH LDH could not exchange with the MO molecule. Thus, it could be concluded that the enhanced adsorption performance of the Mg-Al-OH LDH precursor toward MO is a result of the disorderly state of the precursor, which could provide more adsorption sites than the closed structure of the LDH.…”

“…A better adsorption performance of the precursor toward MO without light irradiation was also observed with an 84% removal rate for the precursor and 56% for the LDH, where a similar improvement in adsorption capacity by the precursor to that of the synthesized LDH was reported for the Mg-Al LDH sample. 18 Although a further decrease in the remaining MO concentrations aer the treatment of light irradiation to the adsorption operation was observed on both the precursor and LDH samples, a larger decrease by 15.23 mg L À1 was observed with the precursor than that of the LDH sample by 7.10 mg L À1 , which indicates higher photocatalytic activity by the precursor sample. It is understood that it is more difficult for the photocatalyst to degrade pollutants at low concentrations.…”

“…The dry milling sample, which is known as the precursor, was found to be an excellent anion adsorbent toward anion organic or inorganic pollutants in our recently published works. Wang et al 18 compared the MO adsorption performance of the precursor of Mg-Al LDH, which was prepared by the dry milling of magnesium hydroxide and aluminum hydroxide, with that of well-crystallized Mg-Al LDH products and found that the precursor showed an obviously higher adsorption capacity toward MO. The precursor of ettringite, which was prepared by the dry milling of dihydrate calcium sulfate, calcium hydroxide and aluminum hydroxide, also possessed a much higher adsorption capacity toward phosphate than that of ettringite.…”

Preparation of Layered Double Hydroxides toward Precisely Designed Hierarchical Organization

“…Second wet milling step was replaced by agitation to increase the crystallinity. The mixture of Mg(OH) 2 and Al(OH) 3 was milled for 1 h using planetary ball mill; then, the mixture was agitated in water for 1-5 h at room temperature [149]. The XRD result showed the increased crystallinity of LDH observed by the increasing of the sharpness of the diffraction peak when prolonging the agitation time.…”